In various industries such as agricultural commodity handling, oil and gas fracturing operations, and the like large quantities of bulk granular material must be received in a storage facility and then transferred from the facility into transport vehicles.
For example USC LLP of Sabetha, Kans. manufactures and sells a transfer system for use in handling agricultural commodities. An elevator framework is erected extending the length of a string of bins to support upper and lower rails, and a vertical bucket elevator is mounted on the rails. A lower transfer conveyor receives product from a transport vehicle and delivers same to the bottom of the bucket elevator, and an upper transfer conveyor at the top of the bucket elevator receives the product and carries same laterally to a fill hatch at the top of each bin. The bucket elevator moves along the rails to transfer product into any of the selected bins.
Typically the bins are hoppered and elevated on legs and a belt conveyor extends along the string of bins under the aligned discharge openings of the bins. The discharge opening of any selected bin can thus be opened and the contents will be carried to the end of the conveyor to be deposited in another transfer conveyor and transferred to a transport vehicle. The USC system is mainly practical for use where a permanent bulk handling facility is required, as the elevator framework must be erected and secured on a foundation to support the bucket elevator. In some situations, large quantities of bulk granular material are needed only temporarily at a work site, such as where concrete is mixed on site for a large concrete pour. U.S. Pat. No. 6,293,689 to Guntert et al. for example discloses a portable concrete batching and mixing plant comprising bins, conveyors and the like mounted on trucks for transport and temporary set up at a construction site.
Longer term temporary bulk storage facilities are often required as well, for example in newly discovered and developed oil fields fracturing of formations in newly drilled wells may take place for some months or years, requiring significant quantities of bulk granular material such as frac sand for this initial period only, and then it would be desirable to be able to conveniently and economically move the facility to another active location.
A problem with such storage facilities at some sites, such as oil well sites, is the limited space available for the facility. In temporary sites as well where the silos are not permanently anchored to the ground, wind loading on the silos, especially when empty, can cause the silos to move. The silos are typically quite high compared to the size of the base, and so there is a risk the silos may tip over in high winds.